Dataset.
We use Copydays   dataset “strong” subset which has 157 images in the Database and \(3,212\)  images as Queries. We augment the data with 10K random distractor images from YFCC100M [1]} following previous works [2]}, [3]} and denote this setting as CD10K. Image retrieval benefits from PCA whitening and thus we use an additional 20K images from YFCC100M following  [3]}, [2]} to train PCA whitening.
